well the author could go off the historical rails again, he did openly at least once or twice (riboku defeated), every other time it was a reinterpretation before (i.e. get framed for rebellion)
white haired boi already mentioned regicide was on the table, would be cool to see them start a civil war then run off and retire after springing him, although i'm not really sure rubickcube and every officer in zhao loyal to him (presumably all of them) could beat 100k elite soldiers that are sworn to the king in typical bad ancient fashion.
edit: the royal messenger soldiers speedblitzed riboku's leftover officers, which is only kaine, but still...
and qin so far hasn't been shown to use that one tactic from the records here, so maybe that wont happen